renders the former carbonyl carbon acidic. After protection of the hydroxyl group with an acyl or silyl group, cyanohydrins can function essentially as masked acyl anions. Because ester protecting groups are base labile, mild bases must be employed with ester-protected cyanohydrins. α-(Dialkylamino)nitriles can also be used in this context. Examples of arylation and acylation reactions are shown below. Although intermolecular arylations using nitrile anions result in modest yields, the intramolecular procedure efficiently gives four-, five-, and six-membered benzo-fused rings. Acylation can be accomplished using a wide variety of acyl electrophiles, including carbonates, chloroformates, esters, anyhdrides, and acid chlorides. In these reactions, two equivalents of base are used to drive the reaction towards acylated product—the acylated product is more acidic than the starting material. Polyalkylation Polyalkylation is a significant problem for primary or secondary nitriles; however, a number of solutions to this problem exist. Alkylation of cyanoacetates followed by decarboxylation provides one solution. Polyanions of nitriles can also be generated by multiple deprotonations, and these species produce polyalkylated products in the presence of alkyl electrophiles. Synthetic applications Alkylation of a nitrile anion followed by reductive decyanation was employed in the synthesis of (Z)-9-dodecen-1-yl acetate, the sex pheromone of Paralobesia viteana. References Nitriles Anions Reactive intermediates